In a conventional engine with a kick-type starting device, such as in a motorcycle, particularly when the engine has a single cylinder of large displacement, the resistance in the compression stroke at the time of starting the engine is so high that a large treading force and great skill are required. Thus, the kicking operation is difficult. In the operation of starting the engine by treading the kick-pedal, if the decompression valve or exhaust valve is opened within a range of a fixed area of this operation to decompress the cylinder, the operability of starting the engine will become easy.
A decompressing device at the time of starting the engine wherein a manual operation is used has already been suggested. However, the synchronization of the kick-starting operation and decompressing manual operation is very difficult.
Therefore, various means of carrying out the decompressing operation is operatively connected with the kicking operation have been suggested. In most such kick-starter devices operatively connected with a decompressing device, there are required several complicated mechanisms, such as a plurality of cams and links, and the reliability of the decompressing operation is poor.
Particularly, the operation of decompressing the engine may be made only in a fixed period in the kick-arm treading stroke. Decompression after the engine starts will cause the engine to stop or will cause troubles, such as the generation of noise. Thus, the engine should not be decompressed except in a required minimum period. In the conventional device, in attempting to solve the decompression problems, the structure is complicated, the reliability of the operation is poor, and the decompression continues for an unnecessary period.
Japanese Utility Model Laid-open No. 3324/1972 (Application No. 36158/1971) suggests a structure to solve the problems of the conventional devices. Therein, a cam is rotated by a kick-starter spindle, and the cam is provided adjacent to a fixed member. A terminal metal fixture of a cable operating a decompression valve is inserted between the cam and fixed member. By treading the kick-starter, the cam is rotated by the spindle. By the rotation of the cam, the metal fixture is slid continuously while being held between the cam and fixed member, and thereby the cable is pulled and the decompression valve is operated. In such device, because the cable terminal metal fixture is slid between the cam and fixed wall, the reliability of the operation is poor. Further, the metal fixture will bite in, and will likely cause a faulty operation due to wear by the repetition of the sliding between the cam and fixed wall. Because the metal fixture is held and slid at two points of the cam and fixed wall, it will incur much wear. When such a worn situation occurs, repair will be a problem.